Technical Field
The present invention relates generally to semiconductor devices, and more specifically, to methods and devices for reducing a thickness of an interfacial layer.
Description of the Related Art
In the quest for improved performance, electronic circuits are becoming denser and devices are becoming smaller. For example, the most common gate dielectric in metal-oxide semiconductor field-effect transistors (MOSFETs) has been SiO2. However, as the thickness of SiO2 approaches 15 Å, substantial issues appear, including large leakage currents through the gate dielectric, concerns about the long-term dielectric reliability, and difficulty of manufacture and thickness control. A solution to the problem is to use thick films of materials, such as hafnium oxide (HfO2) and/or zirconium oxide (ZrO2) which have a dielectric constant larger than SiO2.
High-k dielectrics, such as HfO2, ZrO2, or Al2O3, have dielectric constants more than double the dielectric constant of SiO2 (k=4) and are thus an attractive material for replacement of SiO2 in transistors and capacitors. The term “high-k” denotes a dielectric having a dielectric constant of greater than SiO2, preferably 7 or above. Therefore, the physical thickness of the gate dielectric can be large, while the electrical equivalent thickness relative to SiO2 films can be scaled.